Phrase Origins

In Shakespeare's time, mattresses were secured on bed frames by ropes. When you pulled on the ropes, the mattress tightened, making the bed firmer to sleep on. Hence the phrase, "Good night, sleep tight."

The burning of lime to create a strong light was originally used by lighthouses before the era of electric lights. Theatres also burned lime to create a strong spotlight effect, and led to the expression "in the limelight."